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CYStech Electronics Corp.
Three Terminal Adjustable Output Positive Voltage Regulators
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 1/9
LM317L3
The LM317L3 is an adjustable 3-terminal positive voltage regulator capable of supplying in excess of 1.5A over an output voltage range of 1.2 V to 37 V. This voltage regulator is exceptionally easy to use and requires only two external resistors to set the output voltage. Further, it employs internal current limiting, thermal shutdown and safe area compensation, making it essentially blow-out proof. The LM317L3 serves a wide variety of applications including local, on-card regulation. This device can also be used to make a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM317L3 can be used as a precision current regulator. Output Current in Excess of 1.5 A Output Adjustable between 1.2 V and 37 V Internal Thermal Overload Protection Internal Short Circuit Current Limiting Constant with Temperature Output Transistor Safe-Area Compensation Floating Operation for High Voltage Applications Eliminates Stocking many Fixed Voltages
Standard Application
Vin
LM317 PL317
+
Vout R1
+
Cin is required if regulator is located an appreciate distance from power supply filter. Cout is not needed for stability, however, it does improve transient response.
IAdj
R2
Cin
Cout
0.1F
1.0F
Vout=1.25(1+R2/R1)+IAdjR2 Since IAdj is controlled to less than 100 A, the
error associated with this term is negligible in most applications.
Package Information
Pin 1 2 3 Function ADJ OUTPUT INPUT
1
2
3
SOT-223
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
Maximum Ratings
Rating Input-Output Voltage Differential Power Dissipation TA=25 Operating Junction Temperature Range Storage Temperature Range Symbol VI-VO PD TJ Tstg
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 2/9
Value 40 Internally Limited -40 to +125 -65 to +150
Unit V W
Electrical Characteristics(VI-VO=5V,IO=0.5A,TJ=0 to 125, unless otherwise noted)
Characteristics Line Regulation(Note 1) Load Regulation(Note 1) Symbol Conditions Reg line TA=25,3.0VVI-VO40V Reg load TA=25,10mAIO1.5A VO5.0V VO5.0V Thermal Regulation(Note 4) Reg therm TA=25, 20ms pulse Adjust Pin Current IAdj 2.5VVI-VO40V,10mAIL1.5A Adjust Pin Current Change IAdj PD5W 3.0VVI-VO40V,10mAIO1.5A Reference Voltage Vref PD5W Temperature Stability Ts 0TJ125 Minimum Load Current to ILmin VI-VO=40V maintain Regulation Maximum Output Current Imax VI-VO15V,PD5W VI-VO40V,PD5W,TA=25 % of VO,TA=25,10Hzf10kHz RMS Noise N Ripple Rejection(Note 2) RR VO=10V,f=120Hz Without CAdj CAdj=10F Long-Term Stability(Note 3) S TJ=125,TA=25 for endpoint measurements Min 1.2 1. 5 0.15 66 Typ 0.01 5.0 0.1 0.03 50 0.2 1.25 0.7 3.5 2.2 0.4 0.003 65 80 0.3 Max 0.04 25 0.5 0.07 100 5.0 1.3 10 1.0 Unit %/V mV %VO %VO/W A A V %VO mA A %VO dB %/1.0k Hrs
Notes:1.Load and line regulation are specified at constant junction temperature. Changes in VO due to heating effects must be
taken into account separately. Pulse testing with low duty cycle is used. 2.CAdj, when used, is connected between the adjustment pin and ground. 3.Since long-term stability cannot be measured on each device before shipment, this specification is an engineering estimate of average stability from lot to lot. 4.Power dissipation within an IC voltage regulator produces a temperature gradient on the die, affecting individual IC components on the die. These effects can be minimized by proper integrated circuit design and layout techniques. Thermal regulation is the effect of these temperature gradients on the output voltage and is expressed in percentage of output change per watt of power change in a specified time.
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
Representative Schematic Diagram
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 3/9
Vin
Vout Adjust
VOH-VOL Line Regulation(%/V)= VOL x100
Pulse testing required 1% Duty Cycle is suggested
Fig 1. Line Regulation and IAdj/Line test circuit
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 4/9
Vo(min load)-Vo(max load) Load Regulation(mV)=Vo(min load)-Vo(max load) Load Regulation(%Vo)= Vo(min load) x100
Fig 2. Load Regulation and IAdj/Load test circuit
Pulse testing required. 1% Duty Cycle is suggested.
To calculate R2: Vout=ISETR2+1.250V Assume ISET=5.25mA
Fig 3. Standard Test Circuit
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 5/9
Fig 4. Ripple Rejection Test Circuit
Application Information
Basic Circuit Operation The LM317 is a 3-terminal floating regulator. In operation, the LM317 develops and maintains a nominal 1.25V reference (Vref) between its output and adjustment terminals. This reference voltage is converted to a programming current (Iprog) by R1(see Fig 5), and this constant current flows through R2 to ground. The regulated output voltage is given by: Vout=Vref(1+R2/R1)+IAdjR2 Since the current from the adjustment terminal (IAdj) represents an error term in the equation, the LM317 was designed to control IAdj to less than 100 A and keep it constant. To do this, all quiescent operating current is returned to the output terminal. This imposes the requirement for a minimum load current. If the load current is less than this minimum, the output voltage will rise. Since the LM317 is a floating regulator, it is only the voltage differential across the circuit which is important to performance, and operation at high voltages with respect to ground is possible.
Fig 5. Basic Circuit Configuration
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 6/9
Load Regulation The LM317 is capable of providing extremely good load regulation, but a few precautions are needed to obtain maximum performance. For best performance, the programming resistor (R1) should be connected as close to the regulator as possible to minimize line drops which effectively appear in series with the reference, thereby degrading regulation. The ground end of R2 can be returned near the load ground to provide remote ground sensing and improve load regulation. External Capacitors A 0.1F disc or 1.0F tantalum input bypass capacitor (Cin) is recommended to reduce the sensitivity to input line impedance. The adjustment terminal may be bypassed to ground to improve ripple rejection. This capacitor (CAdj) prevents ripple from being amplified as the output voltage is increased. A 10F capacitor should improve ripple rejection about 15 dB at 120 Hz in a 10V application. Although the LM317 is stable with no output capacitance, like any feedback circuit, certain values of external capacitance can cause excessive ringing. An output capacitance (Co) in the form of a 1.0F tantalum or 25F aluminum electrolytic capacitor on the output swamps this effect and insures stability. Protection Diodes When external capacitors are used with any IC regulator, it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. Fig 6 shows the LM317 with the recommended protection diodes for output voltages in excess of 25V or high capacitance values (Co>25F,CAdj>10F). Diode D1 prevents Co from discharging thru the IC during an input short circuit. Diode D2 protects against capacitor CAdj discharging through the IC during an output short circuit. The combination of diodes D1 and D2 prevents CAdj from discharging through the IC during an input short circuit.
Fig 6. Voltage Regulator with Protection Diodes
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
Application Circuits
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 7/9
Fig 7. "Laboratory" Power Supply with Adjustable Current Limit and Output Voltage
R1=Vref/(Iomax+IDSS) R2Vref/IDSS VoFig 8. Adjustable Current Limiter
LM317L3
Fig 9. 5.0V Electronic Shutdown Regulator
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 8/9
Fig 10. Slow Turn-on Regulator
Fig 11. Current Regulator
LM317L3
CYStek Product Specification
CYStech Electronics Corp.
SOT-223 Dimension
A
Spec. No. : C513L3 Issued Date : 2003.04.09 Revised Date :2005.05.03 Page No. : 9/9
Marking:
B 1 2 3
C
317
D E F G H a1 I a2
Style: Pin 1.Adj 2.Output 3.Input
3-Lead SOT-223 Plastic Surface Mounted Package CYStek Package Code: L3
*: Typical
DIM A B C D E F
Inches Min. Max. 0.1142 0.1220 0.2638 0.2874 0.1299 0.1457 0.0236 0.0315 *0.0906 0.2480 0.2638
Millimeters Min. Max. 2.90 3.10 6.70 7.30 3.30 3.70 0.60 0.80 *2.30 6.30 6.70
DIM G H I a1 a2
Inches Min. Max. 0.0551 0.0709 0.0098 0.0138 0.0008 0.0039 *13o 0o 10 o
Millimeters Min. Max. 1.40 1.80 0.25 0.35 0.02 0.10 *13o 0o 10 o
Notes: 1.Controlling dimension: millimeters.
2.Maximum lead thickness includes lead finish thickness, and minimum lead thickness is the minimum thickness of base material. 3.If there is any question with packing specification or packing method, please contact your local CYStek sales office.
Material:
* Lead: 42 Alloy; solder plating * Mold Compound: Epoxy resin family, flammability solid burning class: UL94V-0
Important Notice:
* All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of CYStek. * CYStek reserves the right to make changes to its products without notice. * CYStek semiconductor products are not warranted to be suitable for use in Life-Support Applications, or systems. * CYStek assumes no liability for any consequence of customer product design, infringement of patents, or application assistance.
LM317L3
CYStek Product Specification

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